When a general popularly known as James “Mad Dog” Mattis abandons a really mad American president, you know something has fallen off the edge in Washington. Since the Roman empire, formerly loyal military chiefs have fled crackpot leaders, and Mattis’s retreat from the White House might have the smell of de Gaulle and Petain about it.

De Gaulle was confronted by an immensely powerful hero of the people – the Lion of Verdun – who was, in his dotage, about to shrug off the sacred alliance with Britain for Nazi collaboration (for which, I suppose, read Putin’s Russia). The decision was made to have nothing to do with Petain, or what Mattis now refers to as “malign actors”. De Gaulle would lead Free France instead.

Mattis has no such ambitions – not yet, at any rate – although there are plenty of Lavals and Weygands waiting to see if Trump chooses one of them for his next secretary of defence. Besides, history should not grant Trump and Mattis such an epic panorama.

After all, no Trump tweet could compare with Petain’s 1916 “We’ll get them!” (“on les aura”) slogan, and the dignified, cold and fastidious de Gaulle would never have lent himself to the rant Mattis embarked upon in San Diego in 2005: “You go into Afghanistan, you got guys who slap women around for five years because they didn’t wear a veil. You know, guys like that ain’t got no manhood left anyway. So it’s a hell of a lot of fun to shoot them. Actually, it’s a lot of fun to fight. You know, it’s a hell of a hoot. It’s fun to shoot some people. I’ll be right upfront with you, I like brawling.”

And Mattis was happy to “brawl” with the Iranians politically, though equally content to let the Saudis do the fighting for him – in Yemen, at least. In 2017, he chose Saudi Arabia to announce that “everywhere you look if there is trouble in the region, you find Iran.” He even thought that “Iran is not an enemy of Isis”, a statement that demonstrated either ignorance or falsehood. No wonder he later became enamoured of Crown Prince Mohamed bin Salman.

But now he has entered a new pantheon. Suddenly the man of war, the US marine general who found it “a hell of a lot of fun” to shoot Afghan misogynists and liked “brawling”, has become a peacemaker. He was the restraining hand tugging at the sleeve of the insane Trump, the one man who could stop Nero burning Rome. He was “the sanest of Trump’s national security team”, according to Paul Waldman in The Washington Post. He was “an island of security”, announced Amos Harel in Israeli newspaper Haaretz.

All this is part of the querulous school of journalism that believed – after Trump’s insanity was made manifest – that the military could control the man in the lunatic asylum. The idea was that while Trump might set light to the world, those trusty generals, veterans of America’s wars for democracy – Afghanistan and Iraq, to be sure – could protect us all from the ravings of a democratically elected president. It’s a grim and dangerous tale in which we have all colluded, especially the Arabs. Better a General Neguib or a Colonel Nasser than corrupt old King Farouk; much safer a Field Marshal Sissi than an unbalanced Muslim Brotherhood man like Mohamed Morsi; more secure (as it seemed in 1969) with a forward-looking Colonel Gaddafi than an effete King Idris.

For there is something both initially attractive and deeply immoral in the idea that the warlords can turn into saviours – this notion does apply to Petain too, of course – and that those who have shed blood must be uniquely gifted with the ability to make peace or produce a just society. Not for nothing, only three months ago, did Mattis publicise his constant reading of Marcus Aurelius’s Meditations. “The reason I kept a tattered copy in my rucksack to pull out at times,” he told US military cadets in Virginia, “was it allowed me to look at things with a little distance.” All Americans should read this book, was his message, “especially in Washington DC, with all the political ‘heave and ho’ that I try to keep the department of defence out of.”

But the real message was surely slightly different. The austere philosopher-emperor of second century Rome – who ruled when the empire covered more territory than ever before in its history – believed in a rather bleak world of duty and service and near-agnosticism; in reality far from Mattis’ Catholic upbringing. Marcus Aurelius spent much of his life waging war – including the Roman-Parthian conflict which destroyed Ctesiphon only a few miles from Baghdad – and his son was the blood-boltered Commodus (famously killed by Russell Crowe in Gladiator).

Generals always seem to keep “tattered” copies of the classics in their rucksacks, rather like First World War soldiers. Harold Macmillan lay wounded in a shell hole at Delville Wood, reading Aeschylus’s Prometheusfor 12 hours. But Mattis?

His career, so far, seems to have a faint parallel with Ariel Sharon, the notoriously ruthless and vain Israeli general who, after being held “personally” responsible for failing to prevent the massacre of up to 1,700 Palestinian civilians by Israel’s Lebanese Christian allies in 1982, was feted as a peacemaker when he died. Sharon – the “Bulldozer” or the “Butcher” depending on whether you listened to the Israelis or the Arabs – was the most important proponent of the Israeli colonisation project in the West Bank (which only speeded up after his withdrawal of Jewish colonies from Gaza) and ended his days after a stroke sent him into an eight-year coma.

But his death was greeted as that of a potential saviour. He helped to sabotage the 1993 Oslo “peace process”, yet on his death David Cameron was to speak of Sharon’s “brave” decision to achieve peace, while Bill and Hillary Clinton said that it had been “an honour to work with him”. John Kerry talked of how Sharon “sought to bend the course of history towards peace”. Sharon did not, so far as we know, read Marcus Aurelius. But, so we are told, he liked to listen to violin sonatas.

Yasser Arafat, on the other hand, started off in the west – and in its media – as a Palestinian super-terrorist leader in Beirut who, once he joined in the doomed charade of Oslo, became a peacemaker. He who had once drawn the sword, offered the world the gun or the olive branch, and was going to make the lion sit down with the lamb, etc. But once the Americans, especially Bill Clinton, had persuaded everyone that Arafat had rejected the final Camp David “peace offer”, Arafat became, yet again, a super-terrorist, or “Israel’s Bin Laden”. That was Sharon’s description.

And so the PLO leader, hated then loved then hated all over again, endured months under siege in his mock-capital of Ramallah, died in Paris and was refused burial in Jerusalem. Here was a man, surely, whose body must have been turning even before it was laid in his grave. Gaddafi had a similar track-record. A terrorist when he shipped weapons to the IRA, he was kissed by Tony Blair and became a peacemaker, then reverted to being a bloodthirsty tyrant, after which David Cameron and his chums decided to bomb him. He even wrote a preposterous pseudo-philosophical Green Book.

So with all these military folk see-sawing between war and peace, praised as defenders of Israel or “Palestine” or America or Arabism – after holding guns in their hands or olive leaves or copies of the Aurelius Meditations or listening to violin sonatas or reading their own turgid prose – it’s probably a good idea to hold off on generals for a while. We’ve had a flurry of them running for cover from Trump in the past two years, all keen on service and duty and supposedly “restraining” the crackpot-in-chief before they throw in their hand. In the real world, the politicians are supposed to restrain the generals. Not the other way round.